1. Clinical Overview
Bevacizumab is a recombinant humanized monoclonal IgG1 antibody that selectively binds to and neutralizes the biological activity of human vascular endothelial growth factor (VEGF). By inhibiting VEGF, it prevents its interaction with VEGF receptors (Flt-1 and KDR) on the surface of endothelial cells, thereby inhibiting tumor angiogenesis, a critical process for tumor growth and metastasis. In the Indian context, it is a cornerstone of targeted therapy for various advanced cancers, used in combination with chemotherapy.
| Onset | Duration | Bioavailability |
|---|---|---|
| The pharmacodynamic effect (VEGF inhibition) begins immediately upon achieving therapeutic serum concentrations. Clinical anti-tumor effects (e.g., reduction in tumor perfusion) can be observed within days, but objective tumor response typically takes several weeks to manifest. | The biological effect persists for the duration of the dosing interval, which is typically 2 or 3 weeks, corresponding to its elimination half-life. | 100% (administered via intravenous infusion, achieving complete systemic bioavailability). |
2. Mechanism of Action
Bevacizumab is a humanized monoclonal antibody that binds with high affinity to all biologically active isoforms of human Vascular Endothelial Growth Factor-A (VEGF-A). This binding prevents VEGF-A from interacting with its receptors (VEGFR-1 and VEGFR-2) on the surface of endothelial cells. VEGF is a key mediator of physiological and pathological angiogenesis. By blocking VEGF signaling, bevacizumab inhibits the formation of new tumor vasculature (anti-angiogenesis), normalizes existing abnormal tumor vasculature, and reduces vascular permeability, thereby inhibiting tumor growth and metastasis.
3. Indications & Uses
- Metastatic Colorectal Cancer (mCRC): First-line or second-line treatment in combination with fluoropyrimidine-based chemotherapy.
- Unresectable, Locally Advanced, Recurrent or Metastatic Non-Squamous Non-Small Cell Lung Cancer (NSCLC): In combination with carboplatin and paclitaxel.
- Recurrent Glioblastoma (GBM): As a single agent for progressive disease following prior therapy.
- Metastatic Renal Cell Carcinoma (mRCC): In combination with interferon alfa-2a.
- Persistent, Recurrent, or Metastatic Cervical Cancer: In combination with paclitaxel and cisplatin or paclitaxel and topotecan.
- Epithelial Ovarian, Fallopian Tube, or Primary Peritoneal Cancer: In combination with chemotherapy for advanced stages.
4. Dosage & Administration
Adult Dosage: Dose is weight-based or fixed, depending on indication. Common regimens: 5 mg/kg body weight IV every 2 weeks (for mCRC, GBM, mRCC) OR 7.5 mg/kg body weight IV every 3 weeks (for mCRC) OR 15 mg/kg body weight IV every 3 weeks (for NSCLC, Cervical, Ovarian cancer). The 100mg vial is used as part of the total calculated dose.
Administration: For IV infusion only. NEVER administer as an IV push or bolus. First infusion: Administer over 90 minutes. If well tolerated, second infusion can be over 60 minutes. Subsequent infusions may be given over 30 minutes if the 60-minute infusion was well tolerated. Dilute prescribed dose in 100 mL of 0.9% Sodium Chloride Injection. Do not administer with dextrose solutions. Do not mix with other drugs. Use an in-line, low-protein-binding 0.2 micrometer filter.
5. Side Effects
Common side effects may include:
- Hypertension (25-35%)
- Fatigue/asthenia (up to 70%)
- Proteinuria (20-40%)
- Headache
- Anorexia
- Diarrhea
- Nausea/Vomiting
- Stomatitis
- Epistaxis (nosebleeds)
- Dysphonia (hoarseness)
- Rash/Exfoliative dermatitis
- Lacrimation disorder
- Back pain
- Arthralgia
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Sunitinib, Sorafenib (other VEGF pathway inhibitors) | Increased risk of microangiopathic hemolytic anemia. Concurrent use not recommended. | Major |
| Anthracyclines (e.g., Doxorubicin) | Potential increased risk of cardiotoxicity (congestive heart failure). Monitor cardiac function closely. | Major |
| Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) like Ibuprofen, Diclofenac | Potential increased risk of gastrointestinal perforation and impaired wound healing. Use with caution. | Moderate |
| Anticoagulants (Warfarin, DOACs) and Antiplatelets (Aspirin, Clopidogrel) | Increased risk of severe or fatal hemorrhage. Use with extreme caution; monitor for bleeding. | Major |
| Live Vaccines (e.g., MMR, Varicella, Yellow Fever) | Risk of disseminated infection due to immunosuppression. Avoid during and for at least 6 months after therapy. | Major |
7. Patient Counselling
- DO report any signs of severe headache, vision changes, seizures (symptoms of RPLS) immediately.
- DO monitor your blood pressure regularly as advised by your doctor.
- DO inform all your healthcare providers (including dentists) that you are on bevacizumab before any procedure.
- DO use effective contraception during and for 6 months after treatment.
- DO NOT take over-the-counter NSAIDs (like ibuprofen) without consulting your oncologist.
- DO NOT schedule any elective surgery or dental procedures without discussing with your oncologist.
- DO NOT receive live vaccines during treatment.
8. Toxicology & Storage
Overdose: No specific antidote for overdose. The highest dose tested in humans was 20 mg/kg IV. Expected symptoms would be an exacerbation of known adverse effects: severe hypertension, proteinuria, headache, clinical signs of congestive heart failure, and increased risk of serious hemorrhagic or thrombotic events.
Storage: Store vials in a refrigerator at 2°C to 8°C. Do not freeze. Do not shake. Protect from light. Keep in the outer carton. The diluted solution for infusion should be used immediately. If not used immediately, it may be stored at 2°C to 8°C for up to 24 hours. Do not freeze the diluted solution.